If you can find one, I'd like to see it. I don't see it as evident that a credit sink must be universal in order to function properly, therefore more evidence would be helpful in proving your point.

As far as my understanding goes from doing some reading on game economies is that inflation is caused by too much gold (or credits in this case) in the game economy. People with excess amounts of credits will then be willing to spend exorbiant amounts on even low-value items because they can. By providing "luxury" items such as high-priced vanity items, credits are taken out of the game economy through those with excess credits.

Since the credit hoarders have less excess credit, they are less likely to buy overpriced common items, returning the game economy to some sane level (I've seen articles that actually speak of "sanity checks" when evaluating game economies).

Repair costs are paid by everyone who engages in activities that involve damage and combat-induced death. Repair costs are typically used in games because they are a relatively passive gold sink (relatively because people can actively choose not to partake in combat by avoiding flashpoints and operations - which is what we're seeing). There is a place for them in the game, but when they become excessive to the point of restricting play, they have a negative impact on the game. (Fewer people taking part in ops is not a good thing for the game as a whole.)

The high priced "luxury" items only take credits out of the economy if people buy them.

I doubt that EA/BW will introduce any in game vendors with high priced luxury items as that would take away possible income from the cartel market.

In addition to that, if they did introduce high priced luxury items, you would have people on these forums complaining that those items are too expensive because only the super rich can afford them.

What you are proposing is to trade one argument (repair costs are too high) that affects you personally for a different argument (the luxury item is too expensive) which may not affect you personally.